Calculator Lock - Calc Vault is a free utility and tool application developed by Tech.One for Android. This app allows you to hide your personal pictures and videos from prying eyes. It disguises itself as a standard calculator app, making it difficult for anyone to know that it's a hidden photo and video vault.

The app comes with a password protection feature, ensuring that unauthorized users cannot access your hidden files. Additionally, it allows you to encrypt and decrypt videos and photos, lock them within the app, and hide them on your device storage or SD card. The app also has a feature that enables you to quickly search for pictures, videos, and folders, as well as view photo and video information. You can rename, delete, share, and edit pictures and videos, and the app has a modern photo and video gallery that allows you to zoom in on photos with ease. It also supports custom theme colors, dark mode, and light mode.

However, it's worth noting that for Android 11 and up, the app requires the MANAGE_EXTERNAL_STORAGE permission to work correctly. If you don't grant this permission, the app won't be able to scan, edit, delete, rename, encrypt, or decrypt photo and video files on your device storage.